[llvm] [AMDGPU] Add regbankselect rules for G_ADD/SUB and variants (PR #159860)

[Petar Avramovic via llvm-commits]

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@@ -500,6 +500,24 @@ void RegBankLegalizeHelper::lowerUnpackMinMax(MachineInstr &MI) {
   MI.eraseFromParent();
 }
 
+void RegBankLegalizeHelper::lowerScalarizeV2S16(MachineInstr &MI) {
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petar-avramovic wrote:

It is not this simple, there is no s_add_i16, see the rule
 Uni(S16, {{Sgpr32Trunc}, {Sgpr32AExt, Sgpr32AExt}}) 
need to use 32 bit add, not scalarize

https://github.com/llvm/llvm-project/pull/159860